I am the proud parent of a pack of 4. Three came to me as young dogs and another decided to move in as an adult. We started with one and built up over the years. The main things in my experience were establishing to them that People rule, we pay the bills,don't we? Watch and learn their behavioral cues to you that signal when one is building up a head of steam. Learn what cues they show so you can head it off. I also learned on the dog whisperer, and yes I couldn't have done it without him, that whenever one dog gets aggressive with another. Put the aggressive dog on the floor, tummy exposed. Call the other dog in and let her be around the bully. This affects both of them. The bully learns, I better not do that or I'll have to lay on my back and it shows the passive dog, see I'll help you with this. Sometimes it can be a problem if they share food and water. If this is where they get mad, you either need separate feeding stations or you have to monitor them while they are eating. I know this sounds like a real hassle but what I found was that the aggressive behavior dropped off when we intervened and the passive dog became more confident and less of a target. And, it can be done. What I haven't been able to manage much success with is walking my dogs. I have the four on leases and I am in a wheelchair. The dogs love to play maypole and tangle me and everyone else up, so I have delegated that to other family. It does help if you walk them together. A tired dog is much less likely to have the energy to waste on squables. Good luck and I know it will work out fine. Just remember they are dogs. They won't stope a behavior because you want themn to, they will only stop when you refuse to allow it.